Let-off means for looms



une 14,192?" J. 5. TGDD LET-OFF MEANS .FOR LOOMS Filed Sept. 7,, 1926 A TTOR/VEY l m/m/mn; lYoWrn SIOELA WITNESS Patented June 14, 1927.

UNITED STATES JOHN s. Tenn, or HAWLEY, PENNSYLVANIA.

, LET-OFF MEANS FOR LOOMS.

Application filed September 7, 1926. 1 Serial No. 183,888.

The means usually employed in looms for controlling the letting-off of the warp includes some form of friction brake device active on the warp-beam, as a rope or ropes in some way held taut with one or more turns thereof, around the beam. The friction between the warp-beam and brake device is not always the same, due to changes in atmospheric andother conditions, and in consequence of this, defects occur in the woven fabric which are known to weavers as shiers, barres, starting-marks,'etc.,

tion with looms having let-off mechanisms employingfriction-brake devices, has entirely overcome thedlfficulties alluded to, so that regardless of the nature of the material being woven, the amount of tension which the particular weave requires, atmospheric and other conditions, it makes possible the weaving of fabrics entirely devoid of such defects as I have mentioned.

' In the drawing,

Fig. 1 is a side elevation of the rear portion of a loom, showing the let-01f mechanism and mycompensator; and

Fig. 2 is a rear elevation.

The letofl" or warp beam 1 is shown mounted in rearward extensions 2 of the loom frame 3; its ends are equipped with the usual peripherally grooved sheaves 4 to receive the turns of the ropes or other flexible friction brake devices.

In the present case each of these devices 5 has one end extending around a pulley 6, mounted at some fixed point (as the floor), and these ends are joined by thespiral spring 7; the other ends of said devices are attached to levers 8 pivoted in suitable brackets 9 and having adjustable weights 1O thereon. Each such device between its endshas one or more turns around one of the sheaves 4-, as shown. While I prefer this form of friction-brake let-01f mechanism, others of course may be used.

Myinvention contemplates the employment of two parts, as rollers, around which rection in which the warp tends to move it, being here mounted in a lever structure.

The two lever structures are very similar, except that as shown the forward one, 11, is shorter than the other, 12, so adescription of. one will serve for both. Each comprises two bars or side members 13, a stretcher 14 connecting them rigidly as the rod shown penetrating them and having clamping'nuts lt screwed on its ends against opposite sides of the bars), and the mentioned bendforming. part 15; each of these parts is in the present example a roller having end truunions 15 journaled in the bars of the corresponding leverstructure at their upper ends, that for the lever structure 12 be ing the actual whip-roll (in'such example). of the loom. The lever structures stand in upright position, the shorter one, 11, in advance of the other, 12, and each is fulcrumed on headed studs 16 secured in the loomlever structure is'normally urged from the corresponding end of the other lever structure by a pair of spiral springs 18, such springs beingconnected on'the one hand to the lower ends of the respective bars and on the other to some fixed point, as the floor.

Assume that the brake devices are so set,

V as by adjusting the weights 10, as to offer a given amount of resistance to the advance of the cloth. This resistance is supposed to i be constant in degree, but for the reasons indicated it is not so in practice, so that- (without my compensator) the fabric would contain the faults mentioned. But with my compensator present and controllin the warp whenever the resistance of the brake devices becomes excessive (as if they stick to the sheaves 4) still the warp remains yieldingly held-against movement in the di- 7 tion, What I claim-is:

1. In combination, witlrsupportmg means yieldingly resisted. against the "forward-i strokeof the reed, and thisresistance is al- Ways substantially the same in degree, so

that the successive shots of fillingare packed. With equal pressure by the reed; in other Words, the density of the cloth remains uniform or constant.

I am aware that it has, beeniproposedito arrange theywhip-roll in a loom so as to be movable forwardly subject to yielding resistancef But in practice I find that such does 1 not; operatetoproduce perfect cloth under:all'conditions, especially in the weav ing of' the finerfabrics; In short, I find that it-isessential to the production of'the very superior results which my invent on makes possible thattinpadclition to such a forwardlyryielding roller or equivalent part as: this forwardly yielding whip-roll there besc'anothe-r and rearwardly yielding roller 7 or equivalent part and that this 1s best arranged somewh'at forward of the warp-beam andso that the stretch 19 of warp between the] two rollers will extendv substantially horizontally, or approximately parallel with the main stretch 19 of the warp; in other words, so' thatjustas the movement of the theparts 15in levers they may be otherwise supported soas to be capable of the movements mentioned: without departing from the spirit of my invention.

Having. thus fully and a letvofit' mechanism including, with the revoluble warp-beam, a friction-brake device therefor, a pair ofparts around which the warp extends arrangedtomaintain re- 7 described my invenp I i independently of the other," and yielding verse-bends in the Warp and each normally movable independently of; the; other under the pressure exerted thereon bythe warp in a direction to passthe other, and yielding means normally opposing such movement of each of s'aidpa-rts. r

2. In combination, with supporting means and-alet-otf; mechanism including, with the revoluble warp-beam, a friction-brake device therefor, a vpair of parts-around" which the warp extends arrangedJt-o maintain reverse bends in the warp and each normally movable independently of'the other substantially in'the'direction inwhich the portion of the warp extending therefrom is pulled,

and yielding means normally opposing such movement of each of said parts.

3. In combination, with'suppo ting meansand a let-offmechams'm including, with the revoluble warp-beam, a friction-brake de vice therefor, a pair of 'leverstructures hayingitheir fulcra substantially parallel'with the axis of the warp beam and having parts around WlllOlY the warp extends in reverse bends and being normally movable on their horizontallyrovoluble warp-beam, a friction brake therefor, a pair of upstandinglever structures having their fuicra horizontal and having attheir upper ends parts around which the warp extends in reverse' bends and being normally movable on theirfulcra each means normally opposing movement of the levers in response to pressure excrted on 

